Process for activating a metallocene catalyst supported on silica

Abstract

The invention provides a process for commercial production of syndiotactic polyolefins using a metallocene catalyst supported on silica treated with MAO. The invention includes contacting the supported metallocene catalyst with a trialkylaluminum and aging the catalyst 12 to 24 hours prior to polymerization.

What is claimed as new and desired to be secured by letter of patent of the United States of America is:  
     
       1. A process for supporting a metallocene on a solid treated with alumoxane comprising: 
       forming a solution of a metallocene of the general formula  
       
         
           R″ b (C 5 R 5-b )(C 5 R′ 5-b )MR* v-2    
         
       
       where R″ is a bridge imparting stereorigidity to the structure of the metallocene by connecting the two cyclopentadienyl rings, b is 1 or 0 indicating whether the bridge is present or not, C 5  is a cyclopentadienyl ring, R and R′ are a hydride or a hydrocarbyl from 1-9 carbon atoms, each R and R′ being the same or different, each of the R and R′ groups being capable of forming fluorenyl rings with other R and R′ groups, respectively, in combination with the cyclopentadienyl rings to which they are bonded, each (C 5 R 5-b ) and (C 5 R′ 5-b ) being different but bilateral symmetry existing for each of (C 5 R 5-b ) and (C 5 R′ 5-b ) separately perpendicular to the planes of their C 5  rings, M is a Group IIIB, IVB, VB or VIB metal, R* is a hydride, a halogen or a hydrocarbyl from 1-20 carbon atoms, v is the valence of M, in a nonpolar solvent; 
       forming a slurry of silica treated with alumoxane in a nonpolar solvent;  
       adding the slurry and solution together at room temperature to form a resulting slurry;  
       stirring the resulting slurry;  
       separating a solid metallocene catalyst supported on silica from the solvents;  
       drying the solid;  
       forming a suspension of the solid metallocene catalyst supported on silica in an inert liquid carrier;  
       adding a trialkylaluminum; and  
       aging the mixture of the solid metallocene catalyst supported on silica and the trialkylaluminum 12 to 24 hours.  
     
     
       2. The process as in claim  1  wherein the trialkyl aluminum is of the general formula AlR′ 3  where R′ is an alkyl of from 1-8 carbon atoms and R′ may be the same or different. 
     
     
       3. The process as in claim  2  wherein the trialkylaluminum is trimethyl aluminum, triethyl aluminum or triisobutyl aluminum. 
     
     
       4. The process as in claim  3  wherein the trialkylaluminum is triisobutyl aluminum. 
     
     
       5. A process as in claim  1  wherein the nonpolar solvent is toluene. 
     
     
       6. A process as in claim  1  wherein the metallocene is diphenylmethylene(cyclopentadienyl-9-fluorenyl)zirconium dichloride. 
     
     
       7. A process as in claim  1  wherein M is zirconium. 
     
     
       8. A process as in claim  1  wherein M is a Group IVB metal. 
     
     
       9. A process as in claim  1  wherein the bridge is a hydrocarbyl biradical having 1-20 carbon atoms. 
     
     
       10. A process as in claim  1  wherein the bridge is one carbon atom which is substituted. 
     
     
       11. A process as in claim  1  wherein the bridge is a linear alkylene radical of 1-10 carbon atoms or branched alkyl radicals of 1-20 carbon atoms. 
     
     
       12. A process as in claim  1  wherein the bridge is diphenylmethylene. 
     
     
       13. A process as in claim  1  wherein (C 5 R 5-b ) is unsubstituted cyclopentadienyl. 
     
     
       14. A process as in claim  1  wherein (C 5 R′ 5-b ) is fluorenyl.